1. Field of the Invention
This invention relates to rear dump trailers and more particularly to a rear dump trailer having an arcuate body and adapted to be connected to the fifth wheel of a tractor for transport.
2. Prior Art
Heretofore, rear dump trailers have been formed with arcuate bodies or shells having a king pin on the front end of the trailer removably connected to a fifth wheel on the rear of a tractor for over the road movement. Such rear dump trailers have also been provided with extendible fluid pressure actuated hoists for raising the front end of the trailer at an inclined position of around 35-45 degrees relative to the tractor for rear end gravity dumping of lading from the dump trailer.
The rear end portion of a dump trailer is usually supported by a chassis having two wheeled axles and is mounted on the chassis for pivotal movement about a horizontal axis during unloading. Relatively large loads or forces are provided against the pivotal axis during the unloading operation particularly at the uppermost raised position of the trailer when the trailer is fully loaded. A trailer normally has a transverse bolster adjacent its rear end carrying the pivotal connection secured to the arcuate body. Relatively large loads are transferred between the bolster and the arcuate body or shell and it is desirable that stress concentrations between the bolster and shell be minimized. High stress concentrations oftentimes cause fatigue cracks after prolonged periods of time under maximum load conditions and it is highly desirable that fatigue cracks be minimized or eliminated.
U.S. Pat. No. 3,844,616 dated Oct. 29, 1974 shows a rear dump trailer having a king pin at its forward end portion for connection to the fifth wheel of a tractor. The trailer includes a shell which is in the shape of a half ellipse and is of a uniform thickness. The rear end portion of the trailer body is supported on a chassis having a pair of wheeled axles for pivotal movement about a horizontal axis positioned between the wheeled axles. However, transversely extending side reinforcing members do not extend beneath the shell. A hydraulic cylinder is mounted on the front end of the trailer for raising the front end of the trailer for dumping but cannot be easily removed from the trailer body.
It is common to provide transversely extending reinforcing ribs spaced longitudinally along the length of a trailer body and secured to the outer surface of the trailer body or shell for reinforcing the shell. Trailer bodies or shells have been formed heretofore of an arcuate shape and the reinforcing ribs have been secured to the outer surface of the arcuate shell. However, the reinforcing ribs have not usually been of an arcuate shape. The maximum loading for an arcuate shell, such as a shell of a semicircular shape, is normally exerted along the center of the bottom of the shell. Thus, it is desirable for the most efficient design to have reinforcing ribs of a maximum strength beneath the bottom of the shell. Reinforcing ribs for arcuate shells heretofore have not been formed of a maximum strength or maximum cross sectional area at the bottom of the shell and oftentimes the ribs have not been of an arcuate shape.